Gardening in September: Plants compete for medals in the ‘Plantalympic Games’!

Keith Jordan

It’s official… it has been the wettest summer for a hundred years! Although there have been dry, sunny days with temperatures in the high 20s, heavy downpours have been the most memorable feature of the summer of 2012…. 8th, 10th, 11th June, 7th, 13/14th and 19/20th July and 25th August to name a few dates! New water butts, bought earlier in the year when a long drought year was looming, have overflowed by several times their volume. The amount of water deposited when it has rained has been immense – a worrying sign that a warmer world atmosphere can hold more water vapour? The hope is that it is just a freak season, but ‘wishful thinking’ will not tackle climate change.

One significant storm occurred on the afternoon of 29th July. As I sheltered with many others under marquees at the Cambridge Folk Festival I thought of all the extra weed growth that would occur on my allotment nearby and the extra work that would be needed.September is a critical month in the gardening year – a chance to get the garden or plot in order before the autumn rains come (perhaps it will be drought this year?) and winter. As well-tuned athletes compete at the Paralympics in London many of us will be battling with rampant fast growing weeds.

From my own experience this summer, the Bronze Medal for rampant growth has gone to Horsetail (Marestail or Equisetum) – a primitive ‘fern-like’ plant with similarities to those that lived when dinosaurs roamed the Earth. They have very narrow leaves and long-lasting roots that creep in from adjacent plots. As fast as you cut the stems, they grow back. It’s a very difficult weed to control – even for people who use herbicides. Digging out roots and using heavy mulches for over a year will gradually weaken them. I use the cut stems as mulching materials in dry periods and tight bunches of the silica-rich leaves can be used as a brillo-pad alternative for cleaning pots and pans. Giver it a try! They can quietly take over allotments with their underground roots but fortunately the plants only grow to about 2 foot.

The Silver Medal has gone to Bramble (or blackberry) that is now six foot on a neighbouring allotment plot. I cut it down a few years ago but the stems that grow some 2 – 3 metres or more a year quickly colonise new ground. Their tips root when they touch the ground meaning they can colonise large areas in a few years. The fruits of wild blackberries are some of the finest, but the plants have to be kept in order or they will take over.

This year, and by a large record-breaking margin, Hedge Bindweed has taken the Gold Medal . The white trumpet-shaped flowers on the ends of long twinning stems currently dominate many allotments, hedgerows, municipal and supermarket shrubberies. Their stems can grow many feet in a season, strangling neighbouring plants. The smaller Field Bindweed can dominate plants at a lower level. This wet year the aforementioned (Silver-medal winning) bramble patch was completely swamped by the bindweed, meaning that even the tasty fruits were unavailable to pick! The roots will remain after the foliage has died down. Eradicating it can take a couple of seasons using mulching, hoeing and digging out the roots.

It can take the determination and persistence of an Olympian to control some of these perennial weeds but endurance in the face of adversity can win through given time! Plants, just like human, have a desire to compete – it all goes on very quietly and slower – but the rivalry is on a par with Usain Bolt and his contemporaries. In all ecosystems there is stiff competition between plants to grow, colonise and take over new areas, but often they are checked by the growth of other plants or pests. In wild areas nettles, docks and other plants can out compete other, less vigorous plants, where nutrient levels are high (perhaps former human habitation where nutrient levels have built up). In your kitchen garden you can use this feature to good effect; enrich your soil with organic compost that contains the whole range of nutrients and soil improving properties – good crop growth (in addition to weeding when crops are small) in time will help suppress unwanted plants. Growing plants closely together can be effective. A completely bramble-infested flower border at a community centre I tackled last year is 95% weed free in one year after digging out the main bramble roots then planting up with plants so closely, most weeds don’t get a look in. Sowing green manure plants (like mustard, phacelia, etc.) now on any vacant soil now will stop other weed seedlings from growing. Broadcast the seeds in blocks so they grow in a dense swathe.

Putting ground weed-infested ground to grass and mowing it regularly for a year or two can be very effective at getting rid of taller, vigorous weeds due to the plant competition. Ironically, I have found that a dense thicket of bramble can actually shade out the (bronze awarded) horsetail and other shorter weeds, but you need to stop the bindweed growing over it!

In conclusion, use the spirit of the London 2012 Olympics/Paralympics to get your vegetable patch in good order this autumn – the lasting legacy could be good crops next season and the years to come!